This section provides background information related to the present disclosure which is not necessarily prior art.
In performing a procedure, a user, such as a surgeon, can perform a procedure on a subject with a navigation system. The navigation system can assist in determining a location of a tracked device, such as a scalpel, catheter, or deep brain stimulation probe, by tracking a tracking device associated with the tracked device. The tracked device can include the instruments noted above, to which a tracking device is associated, such as directly affixed thereto. The instrument can allow a procedure to be performed on a subject while illustrating the location of the instrument relative to the subject. The position of the instrument can be illustrated relative to the subject by superimposing an icon representing the instrument on an image of the subject.
Image data is often acquired of the subject for display prior to, during, and after a procedure on the subject. The image, including the image data which generates or is used to render the image, can be registered to the subject. The image data can define an image space that can include a three-dimensional space. The subject can likewise define a three-dimensional physical space to which the image data is registered. Registration can be performed in a plurality of processes.
According to various embodiments, a navigation system can use an electromagnetic navigation system (EM navigation system) to acquire or determine navigation information, including tracked locations of various tracking devices and relative locations to registered image data. In an EM navigation system, an electromagnetic field (EM field) is generated by a localizer and sensed by a tracking device. The localizer can be positioned relative to the subject space and a tracking device can be associated or positioned on the instrument, or vice versa. According to various embodiments, a localizer can be positioned on the instrument that can generate the EM field to be sensed by a tracking device positioned away from the instrument. It is understood that the EM field can be affected by conducting materials, such as metals or other conducting materials (e.g., conducting polymers or impregnated polymeric materials or devices), and magnetic materials (e.g. soft ferromagnetic iron).